Filament Inspection

Turn the ignition switch to ON position.
Turn the rear window defroster switch on.
CAUTION:
- Directly touching the rear window defroster filament with the lead of the circuit tester will damage it. Wrap aluminum foil around the end of the lead and test the filament by touching it with the foil.
Fig 1: Inspecting Filament
Courtesy of MAZDA MOTORS CORP.
Connect the positive (+) lead of the voltmeter to the positive side of each filament and the negative (-) lead to ground.

Gradually, slide the positive (+) lead from the positive side to the negative side and measure the voltage. Verify that the voltage decrease accordingly.

If the voltage is not as specified or it changes rapidly, the filament is faulty. Repair the filament

Measurement place	voltage (Reference value)
(1) --> (2)	Approx.12 V --> Approx.0 V

Fig 2: Connecting Voltmeter To Filament

Courtesy of MAZDA MOTORS CORP.